Lubricating composition containing non-ash forming additives



United States Patent 3,249,545 LUBRICATING COMPOSITION CONTAINING NON-ASH FORMING ADDITIVES Henricus G. P. van der Voort, Maurits Krukziener, Jan B. Baurdoux, and Hendrik van Oosten, Amsterdam, Netherlands, assignors to Shell Oil Company, New York, N.Y., a corporation of Delaware No Drawing. 'Filed Oct. 12, 1962, Ser. No. 230,279 Claims priority, application Netherlands, Mar. 23, 1962,

3 Claims. (51. 2s2-49.s

ever, tend to form metallic deposits in engine parts which interfere with the effective operation of the engine. In the lubrication of combustion engines with a lubricant containing a metallic additive, the ash deposits formed in the combustion chamber and on the valves causes engine operating difiiculties as, for instance premature ignition of the air/fuel mixture, etc. Because of these deficiencies attributable to ash-containing additives, ashless additives have been developed such as non-ash forming basic and essentially neutral nitrogen-containing dispersants of high molecular weight such as copolymers of polymerizable amines or amides with long-chain acrylate esters. Ashless additives of this type are available commercially under the trade names of LOA-564 or 565, Acryloid 315X, 917 or 966 and described in US Patent 2,737,469 and Belgian Patent 550,422 respectively. These non-ash forming polymeric compounds are good detergents but under extreme pressure conditions lack stability and wear inhibiting properties and are also inefiective as sludge and corrosion inhibitors. Attempts to overcome these deficiencies by modification of these polymers or by use of auxiliary additives in combination with these polymers has met with little success. Thus modifying polymers by introducing certain groups tends often to destroy or reduce the original desirable properties which the polymers possess. In certain cases where auxiliary additives appear to be promising stabilizers and wear inhibitors they are usually metalcontaining compounds such as metal sulfonates or metal carboxylates. For reasons stated, compounds of this type are to be avoided and because of their tendency to com plex with the polymer and form sludge.

It is an object of the present invention to provide an improved non-ash forming lubricating oil composition. It is another object of the invention to provide an improved detergent lubricant possessing good stability and anti-wear properties. Still another object of the invention is to provide a corrosion and .sludge resistant non-ash containing lubricating oil composition. Other objects will become ap parent during the following description of the invention.

Now in accordance with the present invention, it has been found that stability, as well as sludge, wear and corrosion inhibition can be imparted to lubricating oil composition by incorporating therein small amount of (1) an oil-soluble detergent copolymer of (A) an ester of an unsaturated monocarboxylic acid and a monohydric aliphatic alcohol having 4-30 carbon atoms and (B) an ester of an unsaturated aliphatic carboxylic acid and a polyhydric al cohol and (2) certain oil-soluble bisphenols which normally are known for the anti-oxidant properties but in combination with detergent copolymers of the present invention functions as a wear and corrosion inhibitor. The

detergent copolymers per se also lack anti-oxidant and Wear inhibiting properties and primarilyare added to lubricants as detergent-dispersant additives. Therefore, the additive combination imparts to base lubricants, unexpected unusual properties.

The copolymeric additives (l) are copolymers with ester groups derived from monomeric esters of unsaturated monocarboxylic acids, such as acrylic acid, methacrylic acid, crotonic acid, tiglic acid and angelic acid, and monohydric alcohols, such as the octanols, lauryl alcohol and stearyl alcohol, and (2) ester groups derived from monomeric esters of unsaturated carboxylic acids as mentioned hereinbefore, and polyhydric alcohols, such as glycols, trivalent alcohols, such as glycerine and higher alcohols, such as erythrytol, pentaerythrytol, mannitol and the like.

Also suitable are copolymers with ester groups derived from di-esters of the alcohols mentioned hereinbefore, and unsaturated dicarboxylic acids, such as maleic acid, fumaric acid, mesaconic acid, citraconic acid and the like. Copolymers with ester groups derived from the aforesaid alcohols and both an unsaturtaed monocarboxylic acid and an unsaturated dicarboxylic acid, for instance a copolymer derived from mixtures of methacrylate esters and di-esters of maleic acid also can be used in composition of the present invention.

In the preparation of the copolymers of the present invention unsaturated monocarboxylic acids, e.g. methacrylic and acrylic acids are preferred and in the case of the polymerizable ester of a polyhydric alcohol unsaturates esters of ethylene glycols are preferred.

The copolymeric esters of groups (A) and (B) can be derived from mixtures of esters from each groups (A) and (B). As for example, copolymers can be prepared by copolymerization of an ester mixture obtained from an unsaturated acid and an alcohol mixture such as coconut fatty alcohols, with esters obtained from an unsaturated acid and a polyhydric alcohol or mixtures of polyhydric alcohols.

The detergent-dispersant copolymers of the present invention can be modified and viscosity index and pour depressant properties imparted thereto by forming crosslinked polymers therefrom by copolymerizing the copolymers of the present invetion with diolefinic compound such as a dimethacrylate ester of ethylene glycol, divinyl esters, e.g. divinyl adipate and the like fully described in Henricus G. P. van der Voorts copending patent application Serial No. 230,278 filed Oct. 12, 1962.

Illustrative examples of copolymers of the present invention are as follows:

COPOLYMER I Copolymer of stearyl methacrylate, lauryl methacrylate and Z-hydroxyethyl methacrylate in the molar ratio of 5 :5 :3. The intrinsic viscosity of the copolymer, determined at 989 C. in an extracted parafiinic lubricating oil distillate, was 0.65 dl./ g.

COPOLYMER II Copolymer of stearyl methacrylate, lauryl methacrylate, Z-hydroxyethyl methacrylate and the dimethacrylate ester of ethylene glycol in the molar ratio of 5 :5 23:0.03. The intrinsic viscosity of the copolymer, determined at 98.9 C. in an extracted parafiinic lubricating oil distillate, was 0.65 dl./ g.

The other additive which is used in combination with the essential detergent copolymeric additive (1) of this invention is (2) an alkylated bisphenol having the formula OH OH wherein R is a hydrocarbyl radical, preferably a C alkyl radical, y is an integer of l to 4, preferably 1 or 2, X stands for S-, SS, Se, -SCH --CH O-CH CHR, CR -(CH NH-, .O, and wherein R stands for methyl or ethyl and m stands for an integer from 1 to 3. The preferred alkylated bisphenols are those having a sulfur bridge or a methylene bridge.

The alkylated bisphenols may contain from 1 to 8 alkyl groups, but preferably they contain from 2 to 6 alkyl groups. Alkylated bisphenols having 4 alkyl groups are particularly preferred. Each of the alkyl groups may contain from 1 to 10 carbon atoms, preferably 2 to 6 carbon atoms and especially 4 carbon atoms. Furthermore, the alkyl groups contained by any particular bisphenol may be the same or different and may also be primary, secondary, or tertiary alkyl groups. Bisphenols containing at least one tertiary alkyl group are particularly preferred.

As examples of the alkylated bispenols which may be used according to' the invention there are mentioned bis 3-ethyl-4-hydroxyphenyl disulfide,

bis 3-methyl-4-propyl-5-hydroxyphenyl) dis-ulfide,

:bis (2-isopropyl-3-butyl-5-hydroxyphenyl) selenide,

2 2'-diethyl-3-tertiary butyl-4.4'-dihydoxy diphenyl sele-nide,

bis 1.2(2z6-di-tertiary butyl-4-hydroxyphenyl)thiaethane,

bis 1.2 (2 5 -di-isopropyl-3-hydroxyphenyl thiaeth ane,

lbiS 3 S-di-tertiary butyl-4-hydroxyphenyl) sulfide,

2 4-di-isolbutyl-3-hydroxybenzyl-2' 4-dipropyl-3 hydroxy-benzyl sulfide,

bis 1.2 3-0 ctyl-5-tertiary butyl-4-hydroxyphenyl ethane,

bis 1.1 (2 6-di-isopropyl4-hydroxyphenyl ethane,

1.2-bis(2 4-di-tertiary pentyl-3-hydroxyphenyl) propane,

bis 2.2(4z5-di-tertiary butyl-Z-hydroxyphenyl)propane,

bis(2-tertiary butyl-5-isopentyl-4-hydroxyphenyl) amine,

bis (3 S-dibutyl-4-hydroxyphenyl ether,

bis (2-: 6-dipropyl-4-hydroxyphenyl) ether.

Examples of alkylated bis-phenols having a sulfur bridge are bis 2 5-dipentyl-4-hydroxyphenyl) sulfide,

bis 2 S-dihexyl-3-hydroxyphenyl) sulfide,

bis(2-methyl-5-tertiary butyl-4-hydroxyphenyl) sulfide, 1

bis (Z-methyI-S-tertiary butyl-6-hydroxyphenyl) sulfide and particularly bis 3-tertiary butyl-5-methyl-2-hydroxyphenyl sulfide.

Examples of alkylated bisphenols having a methylene bridge are his 2 3-di-tertiary butyl-4-hydr-oxyphenyl methane,

bis 2 5 -di-tertairy butyl-4-hydroxyphenyl methane,

bis (2 6-di-tertiary butyl-4-hydroxyphenyl methane,

bis (3 5 -di-tertiary octyl-4-hydroxyphenyl) methane,

bis 3-tertiary butyl-S-tertiary octyl-4-hydroxyphenyl methane,

and especially bis 3 S-di-tertiary butyl-4-hydroxyphenyl methane,

(3,5-ditert-:butyl-3 ,5 '-dimethyl-4: 4'-dihydroxydiphenyl methane,

(3,5 -ditert-.butyl-3',5 '-diisopropyl-4 4'-dihydroxydiphenyl) methane, t

3,5 ,5 '5 '-ditert-butyl-2,4-dihydroxydiphenyl methane.

The alkylated bisphenol may be prepared by any of the methods known in the art of bisphenols as starting materials and condensing them together by any of the established methods.

The lubricating oil compositions according to the invention may be further improved by addition of small amounts of other additives which are metal-free organic phosphorus-containing compounds such as alkyl, cycloalkyl, alkaryl, aralkyl, and aryl phosphites, phosphates,

phosphonates, and their thioderivatives, such as C alkyl phosphites, e.g. di and tributyl, octyl, lauryl, stearyl, cyclohexyl, benzyl, cresyl, phenyl phosphites or phosphates, as well as their thio-derivatives; P S -terpene reaction product; organo phosphonates, e.g. dibutyl methanephosphonate, dibutyl trichl-oromethanephosphonate, dibutyl monochloromethanephosphonate, dibutyl chlorobenzenephosphonate, dibutyl monochloromethanephosphonate, dibutyl chlorobenzenephosphonate and the like. The esters of pentavalent phosphorus acids such as diphenyl, .dicresyl, triphenyl, tricresyl, .trilauryl and tristearyl phosphate, P S -terpene reaction products and mixtures thereof are preferred.

The concentrations of the various components of the lubricant compositions may vary within wide limits. For instance, the copolymers can be used in concentrations varying from 0.1 to 10% by Weight, the bisphenol, in concentrations yarying from 0.01 to 5% by Weight and the phosphorus-containing compound in concentrations varying, for instance, from 0.01 to 5% by weight. Preferably, lubricant compositions are prepared with a content of copolymers varying from 0.5 to 2% by weight, a content of bisphenol varying from 0.5 to 2% by Weight and, if a phosphate, e.g. an aryl phosphate is used, it may vary from 0.5 to 2% by weight. I

Lubricants of divergent nature can be used for preparing the lubricant compositions according to the in vention. In the first place mineral lubricating oils of varying viscosities may be mentioned. Synthetic lubricating oils are, however, also suitable, as well'as lubricating oils containing fatty oils. Lubricating greases can also :be applied.

For preparing the lubricant compositions according to the invention preferably a mineral lubricating oil is used.

In preparing the lubricant composition it may be an advantage first to prepare a concentrated solution of the copolymer, the bisphenol and, if used, thephosphate, in a solvent or a lubricant and subsequently, for instance elsewhere, to dilute the concentrated solution with a lubricant and to remove by distillation under reduced'pressure or by steam distillation. The following are illustrative compositions of the present invention:

Composition A Percent wt. Base oil: extracted parafiinic lubricating oil distillate with a viscosity of 6.82 cs. at 989 C; 97.75 CopolymerI 1.5 Bis(3,5-di-tert-butyl-4-hydroxyphenyl)methane 0.75

Composition B Base oil: as in A 97.75 Copolymer II 1.5 Bis(3,5-di-tert-butyl-4-hydroxyphenyl)methane 0.75

4 Composition C Base oil: extracted paraffinic lubricating oil distillate with a viscosity of 4.5 cs. at 98.9 C 97.75

Composition E Base oil: as in C 99.25 Bis(3,5-di-tert-butyl-4-hydroxyphenyl)methane 0.75

Composition F Base oil: as in C ,96.75 Copolymer I 1.5 Bis 3 ,5 -di-tert-butyl-4-hydroxyphenyl methane 0.75

Triphen'yl phosphate 1.0

The improvement which the additive combination of the present invention impart to lubricating oils is apparent from the test data shown below.

VISCOSITY INDEX The viscosity indices of compositions A and B were determined according to Dean and Davis (A. Bondi, Physical Chemistry of Lubricating Oils, 1951, pp. 50 ff.) and the results of these measurements are given in Table I.

TABLE I Composition A 138 Composition B 144 Base oil A 100-110 ANTI-WEAR EFFECT The anti-wear effect at high load was determined in tests in which the valve system of a four-cylinder Opel engine was lubricated with lubricating oil compositions according to the invention and also in tests in the fourball top.

OPEL TESTS After removal of the pistons and connecting rods the engine was powered by an electric motor. The tension of the loaded valve spring of about 60 kg. was increased to about 85 kg. by inserting a metal disc between spring and spring seat. The speed of the crankshaft was 2920 r.p.m., hence that of the camshaft 1460 r.p.m. The oil temperature was 90 C.; the amount of oil put into the crankcase was 1.25 kg.

The test was continued until the valve tappets became useless owing to particles of metal crumbling away from the camloaded surface. The results of these tests are recorded in Table II.

TABLE 11 Duration Number of Oil composition Test N 0. of test, damaged hours valve tappets 17 85 none 18 82. 5 3- Other additives may also be incorporated into the lubricating composition according to the invention, for ex ample anti-scuffing agents; anti-foaming agents, e.g. silicone polymers; viscosity index improvers, for example polymeric acrylic esters; extreme pressure additive, for example dibenzyl disulfide; rust inhibitors, for example sorbitan monooleate or butyl stearate; oiliness agents, for example acidless tallow, oleic acid and the like.

We claim as our invention:

1. A mineral lubricating 'oil composition comprising a major amount of mineral lubricating oil and from about 0.1% to about 10% of an oil-soluble copolymer of a mixture of dissimilar C1248 alkyl methacrylates and 2- hydroxyethyl methacrylate, the copolymer having an intrinsic viscosity of around 0.65 dl./g. and from about 0.5% to about 2% of bis(3,5-ditertiarybutyl-4-hydroxyphenyl)methane.

2. A mineral lubricating oil composition comprising a major amount of mineral lubricating oil and from about 0.1% to about 10% of an oil-soluble copolymer of stearyl methacrylate,-1auryl methacrylate and 2-hydroxyethyl methacrylate having an intrinsic viscosity of about 0.65 dl./g. and from about 0.5%-to about 2% of bis(3,5- ditertiarybutyl-4-hydroxyphenyl)methane.

3. The composition of claim 2 containing from about 0.5% to about 2% of tricresyl phosphate.

References Cited by the Examiner UNITED STATES PATENTS 2,157,873 5/1939 Van Peski et al. 25249.8 X 2,636,861 4/1953 Watson 25249.8 X 2,681,987 6/1954 Frazier 26078.5 2,892,819 6/1959- Stewart et al. 25256 2,944,086 7/1960 Cofiield 25252 2,998,414 8/1961 West et al. 25256 3,001,942 9/ 1961 Mulvany et al 252-5 6 3,002,959 10/1961 Hicks 260-78.5 X 3,028,367 4/1962 OBrien 26086.1 X 3,056,764 10/1962 Graham et a1 26078.5 X 3,060,226 10/ 1962 Munn 26086.1 X

DANIEL E. WYMAN, Primary Examiner.

L. G. XIARI-IOS, Assistant Examiner. 

2. A MINERAL LUBRICATING OIL COMPOSITION COMPRISING A MAJOR AMOUNT OF MINERAL LUBRICATING OIL AND FROM ABOUT 0.1% TO ABOUT 10% OF AN OIL-SOLUBLE COPOLYMER OF STEARYL METHACRYLATE, LAURYL METHACRYLATE AND 2-HYDROXETHYL METHACRYLATE HAVING AN INTRINSIC VISCOSITY OF ABOUT 0.65 DL./G AND FROM ABOUT 0.5% TO ABOUT 2% OF BIS(3,5-DITERTIARYBUTYL-4-HYDROXYPHENYL)METHANE.
 3. THE COMPOSITION OF CLAIM 2 CONTAINING FROM ABOUT 0.5% TO ABOUT 2% OF TRICRESYL PHOSPHATE. 